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Debernard L.,CNRS Biomechanical Engineering Laboratory | Leclerc G.E.,CNRS Biomechanical Engineering Laboratory | Robert L.,ACRIM Polyclinique Saint Come | Charleux F.,ACRIM Polyclinique Saint Come | Bensamoun S.F.,CNRS Biomechanical Engineering Laboratory
Journal of Musculoskeletal Research | Year: 2013

This study aims to develop a viscoelastic database for muscles (VM: vastus medialis and Sr: sartorius) and subcutaneous adipose tissue with multifrequency magnetic resonance elastography (MMRE) coupled with rheological models. MMRE was performed on 13 subjects, at 70-90-110 Hz, to experimentally assess the elastic properties (μ) of passive and active (20% MVC) muscles. Then, numerical shear modulus (μ) and viscosity (η) were calculated using three rheological models (Voigt, Zener, Springpot). The elastic properties, obtained with the Springpot model, were closer to the experimental data for the different physiological tissues (μSpringpot-VM-Passive = 3.67 ± 0.71 kPa, μSpringpot-Sr = 6.89 ± 1.27 kPa, μ Springpot-Adipose Tissue = 1.61 ± 0.37 kPa) and at different muscle states (μSpringpot-VM-20%MVC = 11.29 ± 1.04 kPa). The viscosity parameter increased with the level of contraction (η-VM-Passive-Springpot = 4.5 ± 1.64 Pa.s versus η-VM-20%MVC-Springpot = 12.14 ± 1.47 Pa.s) and varied with the type of muscle. (η-VM-Passive-Springpot = 4.5 ± 1.64 Pa.s versus η-Sr-Springpot = 6.63 ± 1.27 Pa.s). Similar viscosities were calculated for all tissues and rheological models. These first physiologically realistic viscoelastic parameters could be used by the physicians to better identify and monitor the effects of muscle disorder, and as a database for musculoskeletal model. © 2013 World Scientific Publishing Company.


Chakouch M.K.,CNRS Biomechanical Engineering Laboratory | Charleux F.,ACRIM Polyclinique Saint Come | Bensamoun S.F.,CNRS Biomechanical Engineering Laboratory
PLoS ONE | Year: 2015

Background Pathologies of the muscles can manifest different physiological and functional changes. To adapt treatment, it is necessary to characterize the elastic property (shear modulus) of single muscles. Previous studies have used magnetic resonance elastography (MRE), a technique based on MRI technology, to analyze the mechanical behavior of healthy and pathological muscles. The purpose of this study was to develop protocols using MRE to determine the shear modulus of nine thigh muscles at rest. Methods Twenty-nine healthy volunteers (mean age = 26 ± 3.41 years) with no muscle abnormalities underwent MRE tests (1.5 T MRI). Five MRE protocols were developed to quantify the shear moduli of the nine following thigh muscles at rest: rectus femoris (RF), vastus medialis (VM), vastus intermedius (VI), vastus lateralis (VL), sartorius (Sr), gracilis (Gr), semimembranosus (SM), semitendinosus (ST), and biceps (BC). In addition, the shear modulus of the subcutaneous adipose tissue was analyzed. Results The gracilis, sartorius, and semitendinosus muscles revealed a significantly higher shear modulus (μ-Gr = 6.15 ± 0.45 kPa, μ- Sr = 5.15 ± 0.19 kPa, and μ- ST = 5.32 ± 0.10 kPa, respectively) compared to other tissues (from μ- RF = 3.91 ± 0.16 kPa to μ-VI = 4.23 ± 0.25 kPa). Subcutaneous adipose tissue had the lowest value (μ-adipose tissue = 3.04 ± 0.12 kPa) of all the tissues tested. Conclusion The different elasticities measured between the tissues may be due to variations in the muscles' physiological and architectural compositions. Thus, the present protocol could be applied to injured muscles to identify their behavior of elastic property. Previous studies on muscle pathology found that quantification of the shear modulus could be used as a clinical protocol to identify pathological muscles and to follow-up effects of treatments and therapies. These data could also be used for modelling purposes. © 2015 Chakouch et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Debernard L.,Compiègne University of Technology | Robert L.,ACRIM Polyclinique Saint COme | Charleux F.,ACRIM Polyclinique Saint COme | Bensamoun S.F.,Compiègne University of Technology
Journal of Biomechanics | Year: 2011

The purpose of this study is to characterize the muscle architecture of children and adults using magnetic resonance elastography and ultrasound techniques. Five children (8-12yr) and seven adults (24-58yr) underwent both tests on the vastus medialis muscle at relaxed and contracted (10% and 20% of MVC) states. Longitudinal ultrasonic images were performed in the same area as the phase image showing the shear wave's propagation. Two geometrical parameters were defined: the wave angle (α_MRE) corresponding to the shear wave propagation and the fascicule angle (α_US) tracking the path of fascicles. Moreover, shear modulus was measured at different localizations within the muscle and in the subcutaneous adipose tissue. The association of both techniques demonstrates that the shear wave propagation follows the muscle fascicles path, reflecting the internal muscle architecture. At rest, ultrasound images revealed waves propagating parallel to the children fascicle while adults showed oblique waves corresponding to already oriented (α_US=15.4±2.54°) muscle fascicles. In contraction, the waves' propagation were in an oblique direction for children (α_US_10%MVC=10.6±2.27°, α_US_20%MVC=10.2±2.29°) as well as adults (α_US_10%MVC=15.4±2.54°, α_US_20%MVC=17.2±2.44°). A stiffness variation (1kPa) was found between the upper and lower parts of the adult VM muscle and a lower stiffness (1.85±0.17kPa) was measured in the subcutaneous adipose tissue. This study demonstrates the feasibility of the MRE technique to provide geometrical insights from the children and adults muscles and to characterize different physiological media. © 2010 Elsevier Ltd.


Bensamoun S.F.,Compiègne University of Technology | Dao T.T.,Compiègne University of Technology | Charleux F.,ACRIM Polyclinique Saint Come | Ho Ba Tho M.-C.,Compiègne University of Technology
Journal of Musculoskeletal Research | Year: 2013

The objective is to estimate the vastus medialis (VM) muscle force from multifrequency magnetic resonance elastography (MMRE) tests and to different rheological models (Voigt and springpot). Healthy participants (N = 13) underent multifrequency (70, 90 and 110 Hz) magnetic resonance elastography MMRE tests. Thus, in vivo experimental elastic (μ) properties of the VM in passive and active (20% MVC) conditions ere characterized. Moreover, the muscle viscosity (η) as determined ith Voigt and springpot rheological models, in both muscle states. Subsequently, the VM muscle forces ere calculated ith a generic musculoskeletal model (OpenSIM) here the active and passive shear moduli (μ) ere implemented. The viscosity measured ith the to rheological models increased hen the muscle is contracted. During the stance and the sing phases, the VM tensile forces decrease and the VM force as loer ith the springpot model. It can be noted that during the sing phase, the muscle forces estimated from springpot model shoed a higher standard deviation compared to the Voigt model. This last result may indicate a strong sensitivity of the muscle force to the change of active and passive contractile components in the sing phase of gait. This study provides for the first time an estimation of the muscle tensile forces for loer limb, during human motion, from in vivo experimental muscle mechanical properties. The assessment of individualized muscle forces during motion is valuable for finite element models, increasing the patient specific parameters. This novel muscle database ill be of use for the clinician to better elucidate the muscle pathophysiology and to better monitor the effects of the muscle disease. © 2013 orld Scientific Publishing Company.


Debernard L.,CNRS Biomechanical Engineering Laboratory | Robert L.,ACRIM Polyclinique Saint Come | Charleux F.,ACRIM Polyclinique Saint Come | Bensamoun S.F.,CNRS Biomechanical Engineering Laboratory
Muscle and Nerve | Year: 2013

Introduction: Characterization of muscle elasticity will improve the diagnosis and treatment of muscle disorders. The purpose is to compare the use of magnetic resonance elastography (MRE) and ultrasound elastography (USE) techniques to elucidate the MRE cartography of thigh muscles. Methods: Both elastography techniques were performed on 5 children and 7 adults. Quantitative (MRE) and qualitative (USE) cartographies of muscle elasticity, as a function of muscle state and age, were obtained with shear waves and manual compression of the ultrasound probe, respectively. Results: Similar cartographies of muscle elasticity were obtained with the 2 methods. The combination of both imaging techniques results in an improved depiction of the physiological changes associated with muscle state and age. Conclusions: This study demonstrates the feasibility of MRE for use as a clinical tool in the characterization of neuromuscular pathologies and for assessing the efficacy of specific treatments for muscle related diseases. © 2012 Wiley Periodicals, Inc.


Leclerc G.E.,CNRS Biomechanical Engineering Laboratory | Debernard L.,CNRS Biomechanical Engineering Laboratory | Foucart F.,CNRS Roberval Laboratory (Mechanical Research Unit) | Robert L.,ACRIM Polyclinique Saint Come | And 5 more authors.
Journal of Biomechanics | Year: 2012

The purpose of this study was to create a polymer phantom mimicking the mechanical properties of soft tissues using experimental tests and rheological models.Multifrequency Magnetic Resonance Elastography (MMRE) tests were performed on the present phantom with a pneumatic driver to characterize the viscoelastic (μ, η) properties using Voigt, Maxwell, Zener and Springpot models. To optimize the MMRE protocol, the driver behavior was analyzed with a vibrometer. Moreover, the hyperelastic properties of the phantom were determined using compressive tests and Mooney-Rivlin model.The range of frequency to be used with the round driver was found between 60Hz and 100Hz as it exhibits one type of vibration mode for the membrane. MRE analysis revealed an increase in the shear modulus with frequency reflecting the viscoelastic properties of the phantom showing similar characteristic of soft tissues. Rheological results demonstrated that Springpot model better revealed the viscoelastic properties (μ=3.45kPa, η=6.17Pas) of the phantom and the Mooney-Rivlin coefficients were C 10=1.09.10 -2MPa and C 01=-8.96.10 -3MPa corresponding to μ=3.95kPa.These studies suggest that the phantom, mimicking soft tissue, could be used for preliminary MRE tests to identify the optimal parameters necessary for in vivo investigations. Further developments of the phantom may allow clinicians to more accurately mimic healthy and pathological soft tissues using MRE. © 2012 Elsevier Ltd.


Chakouch M.K.,CNRS Biomechanical Engineering Laboratory | Pouletaut P.,CNRS Biomechanical Engineering Laboratory | Charleux F.,ACRIM Polyclinique Saint Come | Bensamoun S.F.,CNRS Biomechanical Engineering Laboratory
Journal of Magnetic Resonance Imaging | Year: 2016

Purpose To measure the viscoelastic properties of passive thigh muscles using multifrequency magnetic resonance elastography (MMRE) and rheological models. Materials and Methods Four muscles in five volunteers underwent MMRE tests set up inside a 1.5T magnetic resonance imaging (MRI) scanner. Compression excitation was generated with a driver attached around the thigh, and waves were generated at 70, 90, and 110 Hz. In vivo experimental viscoelastic parameters (G(ω) = G′ + i Gâ€) were extracted from the wavelength and attenuation measurements along a local profile in the direction of the wave's displacement. The data-processing method was validated on a phantom using MMRE and RheoSpectris tests. The complex modulus (G(ω)) related to elasticity (μ) and viscosity (η) was then determined using four rheological models. Results Zener was the best-fit model (χ â0.35 kPa) for the rheological parameters of all muscles. Similar behaviors for the elastic components for each muscle were found for the Zener and springpot models. The gracilis muscle showed higher elastic values (about 2 kPa) in both models compared to other muscles. The α-values for each muscle was equivalent to the ratio Gâ€;/G′ at 90 Hz. Conclusion MMRE tests associated with data processing demonstrated that the complex shear modulus G(ω) of passive muscles could be analyzed using two rheological models. The viscoelastic data can be used as a reference for future assessment of muscular dysfunction. © 2015 Wiley Periodicals, Inc.


Bensamoun S.F.,Compiègne University of Technology | Robert L.,ACRIM Polyclinique Saint Come | Leclerc G.E.,Compiègne University of Technology | Debernard L.,Compiègne University of Technology | Charleux F.,ACRIM Polyclinique Saint Come
Clinical Imaging | Year: 2011

To date, non-invasive methods to detect kidney malignancies and mild tumors remain a challenge. The purpose of this study was to establish the proper imaging protocol to determine kidney stiffness and its spatial distribution within the various kidney compartments such as the renal sinus, medulla, and cortex. Here, we have used magnetic resonance elastography (MRE) along with coronal oblique acquisition to simultaneously measure kidney stiffness in comparison with other tissues including the liver, spleen, and psoas. © 2011 Elsevier Inc.


Bensamoun S.F.,CNRS Biomechanical Engineering Laboratory | Leclerc G.E.,CNRS Biomechanical Engineering Laboratory | Debernard L.,CNRS Biomechanical Engineering Laboratory | Cheng X.,CNRS Biomechanical Engineering Laboratory | And 4 more authors.
Alcoholism: Clinical and Experimental Research | Year: 2013

Background: Due to the lack of cutoff values validated for specific liver diseases, the purpose of this study was to set up specific magnetic resonance elastography (MRE) cutoff values for asymptomatic liver fibrosis in alcoholic patients. Methods: Ninety patients underwent 3 clinical exams. The liver stiffness was measured locally with the Fibroscan, and globally through cartographies of shear modulus generated with MRE. The Fibroscan method was chosen as the gold standard to classify the fibrosis. The liver score was also obtained with the Fibrometer A, and the diagnostic performance of the methods was analyzed with receiver-operating characteristic (ROC) curves and cutoff values were calculated. Results: Spearman correlation and area under the ROC curve revealed that MRE is a better diagnostic method than the Fibrometer A, to identify various levels of fibrosis. The results showed that the Fibrometer A was adapted for severe fibrosis. The MRE cutoff values are F1:2.20 kPa, F2:2.57 kPa, F3:3.31 kPa, and F4:4 kPa and were not influenced by the glutamic oxaloacetic transaminase level. By using the ultrasound cutoff values attributed for alcoholism, 66% of patients had a similar liver fibrosis diagnosis as the MRE cutoffs. However, both imaging techniques did not provide the same distribution for minor fibrosis. Conclusions: None of the imaging techniques (Fibroscan, MRE) could replace the gold standard of the biopsy. However, due to the risk and the unnecessary procedure for the present recruited alcoholic patients, the Fibroscan method was chosen as the reference. Since MRE is currently being used as a clinical exam, the present MRE cutoffs could aid clinicians with their diagnosis of liver fibrosis for alcoholism disease. © 2012 by the Research Society on Alcoholism.


PubMed | CNRS Biomechanical Engineering Laboratory and ACRIM Polyclinique Saint Come
Type: Journal Article | Journal: Journal of magnetic resonance imaging : JMRI | Year: 2016

To measure the viscoelastic properties of passive thigh muscles using multifrequency magnetic resonance elastography (MMRE) and rheological models.Four muscles in five volunteers underwent MMRE tests set up inside a 1.5T magnetic resonance imaging (MRI) scanner. Compression excitation was generated with a driver attached around the thigh, and waves were generated at 70, 90, and 110 Hz. In vivo experimental viscoelastic parameters (G() = G + i G) were extracted from the wavelength and attenuation measurements along a local profile in the direction of the waves displacement. The data-processing method was validated on a phantom using MMRE and RheoSpectris tests. The complex modulus (G()) related to elasticity () and viscosity () was then determined using four rheological models.Zener was the best-fit model ( 0.35 kPa) for the rheological parameters of all muscles. Similar behaviors for the elastic components for each muscle were found for the Zener and springpot models. The gracilis muscle showed higher elastic values (about 2 kPa) in both models compared to other muscles. The -values for each muscle was equivalent to the ratio G/G at 90 Hz.MMRE tests associated with data processing demonstrated that the complex shear modulus G() of passive muscles could be analyzed using two rheological models. The viscoelastic data can be used as a reference for future assessment of muscular dysfunction. J. Magn. Reson. Imaging 2015. J. Magn. Reson. Imaging 2016;43:1423-1433.

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